The 'blocker directory name' described in Step #7 of the current multi-device jb is the best that we can do at the moment.
With the newest versions of the 5.8.x firmware, what happens is:
*) Kindle system discovers an OTA update is available.
*) Attempts to save to the user's storage area.
*) Finds the directory name.
*) Suceeds in removing the directory name.
*) Pops up a 'download failed' notice panel.
*) Resets its timer for this entry on the to-do list (about 8 hours later).
It will succeed the next time it tries unless the user takes some action (like put the blocker name back or enables airplane mode).
I think that some of the people here are working on a better method but this is a very loose group of individuals.
Contributors contribute what they already do for themselves.
The other choices are:
*) Keep it in airplane mode.
*) Install the BBB (Block Big Brother) firewall (which hasn't been updated for new Amazon servers - but could be easily, just takes time to read a bunch of log files contributed by owners of the various models).
Note:
Open the credits spoiler of the current jail break directions.
Of the list of people there, there is only one person still active here (guess who).
I do wish I still had the active mind of a 20 year old, but I am over 70 and the aging hasn't been that kind.
So answering questions that I have already seen the answer too is about the best I can do.